class Solution
{
public:
    int countNumbersWithUniqueDigits(int n)
    {
        vector<int> dp(n + 1);
        if (n == 0) return 1;
        if (n == 1) return 10;
        dp[0] = 1;
        dp[1] = 10;
        for (int i = 2; i <= n; i++)
        {
            dp[i] = dp[i - 1] + (dp[i - 1] - dp[i - 2]) * (10 - (i - 1));
        }
        return dp[n];
    }
};